Add assert on frameView::wasViewportResized

Source/core/frame/FrameView.cpp

 /*
  * Copyright (C) 1998, 1999 Torben Weis <weis@kde.org>
  *                     1999 Lars Knoll <knoll@kde.org>
  *                     1999 Antti Koivisto <koivisto@kde.org>
  *                     2000 Dirk Mueller <mueller@kde.org>
  * Copyright (C) 2004, 2005, 2006, 2007, 2008 Apple Inc. All rights reserved.
  *           (C) 2006 Graham Dennis (graham.dennis@gmail.com)
  *           (C) 2006 Alexey Proskuryakov (ap@nypop.com)
  * Copyright (C) 2009 Google Inc. All rights reserved.
  *
@@ skipping 2006 matching lines @@
 
     sendResizeEventIfNeeded();
 }
 
 bool FrameView::wasViewportResized()
 {
     ASSERT(m_frame);
     RenderView* renderView = this->renderView();
     if (!renderView)
         return false;
+    ASSERT(renderView->style());
     return (layoutSize(IncludeScrollbars) != m_lastViewportSize || renderView->style()->zoom() != m_lastZoomFactor);
 }
 
 void FrameView::sendResizeEventIfNeeded()
 {
     ASSERT(m_frame);
 
     RenderView* renderView = this->renderView();
     if (!renderView || renderView->document().printing())
         return;
@@ skipping 1966 matching lines @@
         return;
 
     ScrollableArea::setScrollOrigin(origin);
 
     // Update if the scroll origin changes, since our position will be different if the content size did not change.
     if (updatePositionAtAll && updatePositionSynchronously)
         updateScrollbars(scrollOffsetDouble());
 }
 
 } // namespace blink